Test. Test. And Test Again. How Much Biochar Should You Use?

How Much Biochar Should You Apply?

We are constantly asked the question, “How much biochar should I use?” It’s a great question and the answer isn’t always obvious. From everything we have seen in our own use and through the biochar research of others a good “rule of thumb” is 10% of the planting area should be biochar. If your soil is absolutely horrible you should probably start with a 50/50 mix of biochar and compost and apply about 1/4 lb per square foot. Really bad soil needs a big injection of organic material along with the biochar. Of course, just to keep things moving along we’ve asked for another research project to be conducted at the University of Missouri to take a look at two kinds of plants — radishes and grass. We chose radishes because anecdotal evidence suggests vegetables that grow underground tend to see less improvement in growing than vegetables that grow above ground – tomatoes tend to do very well. Grass was selected because it is such a great opportunity for every parent that has to deal with their lawn most of the year to give them a healthier field of grass that has fewer weeds and stronger root system that is drought resistant.

So, we begin our journey with the Mizzou crew of researchers, Jeff and Dakota. Here is a summary of what they are going to do for us…


Biochar has been around for centuries, but a relatively new agricultural carbon product that is making its way into the hands of the people with help from companies, such as Wakefield. The end product with the right ratio of soil, compost and biochar can produce a re-energized garden or lawn by contributing to healthier soil that produces better yields, help with drought-resistance, soil that lasts much longer than in previous conditions, and is also considered carbon negative.

Proposed Plan: Dakota and Jeff have set up an experiment with Wakefield biochar to test optimal ratios of biochar, compost, and soil to determine how much actual biochar should be used for the consumer buying the product to use in their garden or landscaping. The two current variables we are testing are the different percentages of biochar and compost that we are adding to a 50% soil. Through research, we have discovered that usual biochar products have used 10-20% biochar to their mix and have shown great results. We are testing within that range and a little less (5-8%), as we are also testing the proper amount of water to be added to the ratios of the mix we created to further our results to see what best use Wakefield can have with their biochar. There are also two controls, possibly three, as one control will be 100% soil and the other 100% compost. Our third possible control would be a 50/50 split of compost and soil for further data analysis. Dakota and I are currently waiting a week to allow for the biochar enough time to activate, as Wakefield biochar is 97% carbon and much like a Brita filter in your fridge you must wait for the carbon to activate to help with porosity.

Carbon in biochar if not allowed time to activate can result in a lack of growth to new seeds or plants already planted around the biochar. Biochar acts as a magnet when mixed with soil that pulls and keeps the soil’s nutrients, which keeps the nutrients from leaching out from watering, weathering, planting, etc. In the picture below you can see we have completed the mixing process with all the mixes labeled with the ratios we proposed and are now in the process of waiting for the carbon to activate, so we can plant our radish seeds that we will be using throughout the experiment. We choose radishes because they are a plant that grows underground and one of the things we wanted to find out is if plants that grow underground will be negatively or positively affected by the different biochar ratios.


The main goal in completing a semester of data collecting and research is to become clear on the proper application rate of biochar so that we can easily explain it to Wakefield’s customers. Being able to inform the average person about Wakefield and what they have to offer is extremely important in getting their name out there as a leader in biochar products. Dakota and I will take our data collected and accurately see what the best ratio of biochar to add to the mix of compost and soil so that Wakefield can produce an efficient product that is fair to the buyer and will show the best results.

4 thoughts on “Test. Test. And Test Again. How Much Biochar Should You Use?

  1. Tony Marrero says:

    Edward – Sorry for the delay putting the results online. You can now see the final paper from Dakota Botts online. Search for Dakota above and his final report will be available to you.

  2. Dan Spahr says:

    I’ve just dug out an area for a pond with the intention of making soil because in this area is both sides angle like a Funnel together so as to collect in the area I dug out for a pond. All the plants that I removed I mulched and mixed with the clay so I could start to rebuild this soil now will biochar start this mixed clay mulch into good soil for the garden

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